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  <title>检查文件或目录是否存在</title>

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</div><hr /><div id="function.file-exists" class="refentry">
 <div class="refnamediv">
  <h1 class="refname">file_exists</h1>
  <p class="verinfo">(PHP 4, PHP 5)</p><p class="refpurpose"><span class="refname">file_exists</span> &mdash; <span class="dc-title">检查文件或目录是否存在</span></p>

 </div>
 <div class="refsect1 description" id="refsect1-function.file-exists-description">
  <h3 class="title">说明</h3>
 <div class="methodsynopsis dc-description">
   <span class="type">bool</span> <span class="methodname"><strong>file_exists</strong></span>
    ( <span class="methodparam"><span class="type">string</span> <code class="parameter">$filename</code></span>
   )</div>

    <p class="para rdfs-comment">
     检查文件或目录是否存在。
    </p>
 </div>


 <div class="refsect1 parameters" id="refsect1-function.file-exists-parameters">
  <h3 class="title">参数</h3>
  <p class="para">
   <dl>

    
     <dt>
<em><code class="parameter">filename</code></em></dt>

     <dd>

      <p class="para">
       文件或目录的路径。
      </p>
      <p class="para">
       在 Windows 中要用 <var class="filename">//computername/share/filename</var> 或者
   <var class="filename">\\computername\share\filename</var> 来检查网络中的共享文件。
      </p>
     </dd>

    
   </dl>

  </p>
 </div>


 <div class="refsect1 returnvalues" id="refsect1-function.file-exists-returnvalues">
  <h3 class="title">返回值</h3>
  <p class="para">
   如果由 <em><code class="parameter">filename</code></em> 指定的文件或目录存在则返回
   <strong><code>TRUE</code></strong>，否则返回 <strong><code>FALSE</code></strong>。
  </p>
  <blockquote class="note"><p><strong class="note">Note</strong>: 
   <p class="para">
    This function will return <strong><code>FALSE</code></strong> for symlinks pointing to non-existing
    files.
   </p>
  </p></blockquote>
  <div class="warning"><strong class="warning">Warning</strong>
   <p class="para">
    如果因为<a href="features.safe-mode.html" class="link">安全模式</a>的限制而导致不能访问文件的话，该函数会返回
    <strong><code>FALSE</code></strong>。然而，可以使用
    <a href="function.include.html" class="link">include</a> 来包含，如果文件在
    <a href="ini.sect.safe-mode.html#ini.safe-mode-include-dir" class="link">safe_mode_include_dir</a>
    所指定的目录里。
   </p>
  </div>
  <blockquote class="note"><p><strong class="note">Note</strong>: 
   <p class="para">
    The check is done using the real UID/GID instead of the effective one.
   </p>
  </p></blockquote>
  <blockquote class="note"><p><strong class="note">Note</strong>: <span class="simpara">
因为 PHP 的整数类型是有符号整型而且很多平台使用 32 位整型，对 2GB
以上的文件，一些文件系统函数可能返回无法预期的结果 。</span></p></blockquote>
 </div>


 <div class="refsect1 examples" id="refsect1-function.file-exists-examples">
  <h3 class="title">范例</h3>
  <p class="para">
   <div class="example" id="example-2299">
    <p><strong>Example #1 测试一个文件是否存在</strong></p>
    <div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<span style="color: #0000BB">&lt;?php<br />$filename&nbsp;</span><span style="color: #007700">=&nbsp;</span><span style="color: #DD0000">'/path/to/foo.txt'</span><span style="color: #007700">;<br /><br />if&nbsp;(</span><span style="color: #0000BB">file_exists</span><span style="color: #007700">(</span><span style="color: #0000BB">$filename</span><span style="color: #007700">))&nbsp;{<br />&nbsp;&nbsp;&nbsp;&nbsp;echo&nbsp;</span><span style="color: #DD0000">"The&nbsp;file&nbsp;</span><span style="color: #0000BB">$filename</span><span style="color: #DD0000">&nbsp;exists"</span><span style="color: #007700">;<br />}&nbsp;else&nbsp;{<br />&nbsp;&nbsp;&nbsp;&nbsp;echo&nbsp;</span><span style="color: #DD0000">"The&nbsp;file&nbsp;</span><span style="color: #0000BB">$filename</span><span style="color: #DD0000">&nbsp;does&nbsp;not&nbsp;exist"</span><span style="color: #007700">;<br />}<br /></span><span style="color: #0000BB">?&gt;</span>
</span>
</code></div>
    </div>

   </div>
  </p>
 </div>


 <div class="refsect1 errors" id="refsect1-function.file-exists-errors">
  <h3 class="title">错误／异常</h3>
  <p class="para">
失败时抛出<strong><code>E_WARNING</code></strong>警告。
</p>
 </div>


 <div class="refsect1 notes" id="refsect1-function.file-exists-notes">
  <h3 class="title">注释</h3>
  <blockquote class="note"><p><strong class="note">Note</strong>: <span class="simpara">此函数的结果会被缓存。参见
<span class="function"><a href="function.clearstatcache.html" class="function">clearstatcache()</a></span> 以获得更多细节。</span></p></blockquote>
  <div class="tip"><strong class="tip">Tip</strong><p class="simpara">自 PHP 5.0.0 起, 此函数也用于<em class="emphasis">某些</em>
URL 包装器。请参见 <a href="wrappers.html" class="xref">支持的协议和封装协议</a>以获得支持 <span class="function"><a href="function.stat.html" class="function">stat()</a></span> 系列函数功能的包装器列表。</p></div>
 </div>


 <div class="refsect1 seealso" id="refsect1-function.file-exists-seealso">
  <h3 class="title">参见</h3>
  <p class="para">
   <ul class="simplelist">
    <li class="member"><span class="function"><a href="function.is-readable.html" class="function" rel="rdfs-seeAlso">is_readable()</a> - 判断给定文件名是否可读</span></li>
    <li class="member"><span class="function"><a href="function.is-writable.html" class="function" rel="rdfs-seeAlso">is_writable()</a> - 判断给定的文件名是否可写</span></li>
    <li class="member"><span class="function"><a href="function.is-file.html" class="function" rel="rdfs-seeAlso">is_file()</a> - 判断给定文件名是否为一个正常的文件</span></li>
    <li class="member"><span class="function"><a href="function.file.html" class="function" rel="rdfs-seeAlso">file()</a> - 把整个文件读入一个数组中</span></li>
   </ul>
  </p>
 </div>

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